UVB-protective properties of contact lenses with intended use in photoresponsive eyelid dermatoses.

BACKGROUND UV-blocking contact lenses were evaluated to determine if they could provide adequate ocular protection during narrowband UVB phototherapy treatment. Theoretical safe exposure durations for the crystalline lens, cornea and conjunctiva were determined. METHODS A Cary 500 spectrophometer generated transmittance data for six UV-blocking and two non-UV-blocking contact lenses. An IL-1700 radiometer measured the lenses' radiation transmittance within the NB-UVB phototherapy unit. The lenses were exposed to a 1500-mJ/cm(2) dose of radiation from a 308-nm excimer laser to determine if the radiation would alter their protective properties. Theoretical safe exposure durations for eye structures were calculated using previous human and animal study data. RESULTS All UV-blocking contact lenses showed less than 1E-7 W/cm(2) of radiation transmittance within the narrowband phototherapy unit. The excimer laser did not significantly alter the lenses' UV-blocking capabilities. The safe exposure durations for the cornea and crystalline lens were greater than 11 min with UV-blocking lenses, and that for the unprotected conjunctiva was approximately 11 s. CONCLUSION Some UV-blocking contact lenses potentially provide sufficient ocular protection during narrowband UVB phototherapy treatment, as the crystalline lens and cornea are adequately protected should a patient open his or her eyes for a short time.